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OVERVIEW Need for USG
Mechanics of USG
Principles of lung USG
BLUE protocol
Alveolar syndrome
Interstitial syndrome
Weaning assessment
Pneumonia / VAP
Prone position
ventilation assessment
ETT positioning
Post extubation stridor
Need for USG?? Supplement clinical assessment in critically ill
Stethescope of modern intensivist!!
Absence of radiation, better portability,
real-time imaging, and the ability to
perform dynamic imaging, faster, relatively cheap
Convenience
USG – THEN AND NOW !!!
USG – THEN AND NOW !!!
TRANSDUCERS
Probes
USG – Tissue interactions
MODES OF USG B Mode: Brightness▪2D Image▪Intensity of brightness : strength of echo
M mode: Motion▪What the line see vs time▪Stationary stuff: Straight line▪Moving things: curved/ dot
LUNG USG
LUNG USG
LUNG USG – ARTIFACTS
SCANNING PROCEDURE Position patient, arm
abducted
Adjust depth of usgwindow to 5-8cm
Longitudinal placement of transducer between ribs
Systematic scanning, apex to base of both sides
NORMAL PLEURAL USG
Sonographer should visualise two rib shadows with hyperechoic pleural line moving back and forth
Bat sign
Lung sliding should be seen
LUNG USG: CRITICALLY ILLThe bat sign
The A-line
Lung sliding
The quad sign
The sinusoid sign
The tissue-like sign
The shred sign
The B-line(& lung rockets)
The stratosphere sign
The lung point
The lung pulse
Dynamic air bronchogram
BAT SIGN
Two ribs with posterior shadowing represents the wings of the bat, and the hyperechoic pleural line, its body
Between these two ribs, the two layers of pleura are seen sliding across one another
A LINES
Horizontal lines parallel to chest wall
Brightly echogenic
Located between rib shadows when probe positioned longitudinally
B LINES
Arise at the border between aerated and compressed lung
Multiple ray-like, or comet-tail, vertical lines
Extend from the pleural line to the lower edge of the screen without fading
Move synchronously with the lung during respiration and tend to erase A lines
B LINES
E LINES
Suspected when subcutaneous emphysema can be palpated
Vertical lines start at a level external to the ribs extending deep into chest
Similar to B lines ,but arise from chest wall and not pleural line
LUNG PULSE ( T LINES)
Rhythmic movement of the pleura in synchrony with the cardiac rhythm
Best viewed in areas of the lung adjacent to the heart, at the pleural line
result of cardiac vibrations being transmitted to the lung pleura in poorly aerated lung
QUAD SIGN/SINUSOIDAL SIGN
Characteristic of pleural effusion
"quad sign" - fluid is framed within four borders: pleural line, lung line, acoustic shadows of two ribs (or diaphragm)
"sinusoid sign" - appears in the M-mode as a result of alteration of respiratory transverse interpleural space
SEA SHORE SIGN/ BAR CODE SIGN
Dynamic sign
Best seen at apex in supine position
Present in normal lung
The motionless portion of the chest above the pleural line creates horizontal 'waves,' and the sliding below the pleural line creates a granular pattern, the 'sand‘
LUNG POINT
Defines the border of pneumothorax
Helps in defining size of pneumothorax
Not seen in cases of total lung collapse
Tissue sign & shred sign
TISSUE LIKE SIGN SHRED SIGN
BLUE PROTOCOL Bedside lung
ultrasound in emergency
In <3minutes
Step-by-step diagnosis of the main causes of acute respiratory failure
six diseases seen in 97% of patients in the emergency room with overall 90.5% accuracy
Rantanen NW: Diseases of the thorax. Vet Clin North Am 1986, 2: 49–66
Lichtenstein D: BLUE-protocol. In Whole Body Ultrasonography in the Critically Ill. Heidelberg, Berlin, New York: Springer-Verlag; 2010:189–202
USG: Pnuemothorax
US FOR DIAGNOSIS OF PNEUMOTHORAX
Chan SSW et al Acad Emg Med Jan 2003Vol 10 1
USG : PNEUMOTHORAX
Disappearance of lung sliding in 100%
The lung point is 100% specific for pneumothorax but only moderately sensitive
Sensitivity Specificity
Cxray 52% 99%
USG 88% 100%
Zhang et al ;meta-analysis.CHEST 2011
ALVEOLAR SYNDROME
Atelectasis Pneumonia
intercostal space narrowing
liver and spleen elevated
Compressive atelectasiswithin transudative effusions demonstrates sinusoidal movements of the lung tip with respiration
lung volume is maintained
hyperechoic (hepatization) than atelectasis
Dynamic air bronchograms-94% specific for pneumonia, although sensitivity is only 61%¹
¹D Lichtenstein: The Dynamic Air Bronchogram Chest 2009;135(6)
USG- CONSOLIDATION
Probe at PLAPS point
90% sensitive and 98% specific
No lung sliding with tissue or shred sign
2012 consensus evidence based recommendations: intensive care med (2012) 38:577 - 591
INTERSTITIAL SYNDROME Interstitial syndrome is caused by:
1. Pulmonary oedema - either haemodynamic (fluid
overload, cardiac failure) or permeability induced
(acute lung injury / ARDS)
2. Interstitial pneumonia or pneumonitis
3. Lung fibrosis
INTERSTITIAL SYNDROME
Multiple B lines are the sonographic sign
Ideally-8 region scan
or
rapid 2 region scan
or
28 rib interspaces
(Volpicelli et al, Intensive care medicine 2012 38 577-591)
8 REGION SCAN
Positive: ≥3 B lines
≥2 regions each side
Volpicelli et al, Intensive care medicine 2012 38 577-591
BLUE POINT
TOTAL B LINE SCORE(TBS)
Jambrik et al Am J Cardiol 2004:93 1265-70
TBS was significantly correlated with extra vascular lung water index
Pirompanich P et alCritical Care 2015, 19(Suppl 1):P223
Diagnosis of pulmonary edema
SENSITIVITY SPECIFICITY
TBS ≥ 39 91.7 75
BLUE POINT (+ VE in all 4 regions)
33.3 100
8 REGIONS(+ ve in 2/4 regions each side)
50 96
Pirompanich P et al ,Critical care 2015
Hydrostatic edema vs ARDS Acutely ill patients with hypoxemia and a bilateral B-line
pattern
Ultrasound -detect pleural line abnormalities in ARDS
-thickenings > 2 mm
-evidence of small subpleural
consolidations
-coarse appearance of the pleural line,
(rare in cardiogenic edema)
Areas of sparing are found in 100% of patients with ARDS but are not present in cardiogenic edema
Interstitial syndrome : B3 Vs B7
Ac cardiogenicpulm edema
Chronicheart failure
ARDS Pulm fibrosis
Clinincalsetting
Acute Chronic Acute Chronic
No of B lines ++++ +/++/+++ ++++ +/++/+++
B lines distribution
Multiple,diffuse, B/L
Multiple,diffuse, B/L
Nonhomogenous distribution, spared areas
More frequently base of lungs
Other LUS signs
Pl effusion Pl effusion Pl effusion, consolidations
Pl thickening
ECHO Abnormal Abnormal Likely normal Likely normal
FALLS PROTOCOL
Fluid administration limited by lung sonography
It is the adaptation of BLUE protocol in patients with acute circulatory failure
Simple real time echo with lung ultrasound
Endpoint of fluid therapy- appearence of b lines
USG – Pleural Effusion Confirm the diagnosis, allows distinction btn effusion
and consolidation
Usg(97%) is more accurate than cxray(47%)
Distinction btn transudative and exudative effusion
THORACOCENTESIS
Identify best site to perform puncture
Know the depth of adjacent organs
Reduces complications
USG - Thoracocentesis 211 patients MV patients requiring thoracocentesis
232 usg guided taps were done(by critical care physicians without radiologist support)
Pnuemothorax occured in 3 of 232 (1.3%)
VENTILATOR WEANING
DT assessed by ultrasound is an excellent predictor of weaning outcome in mechanically ventilated COPD patients
DT was significantly different between patients who failed and patients who succeeded SBT
Success of SBT
Sensitivity Specificity PPV NPV
DT > 40% 88 92 95 82
RSBI <105 95 90 96 92
Gamal Agmy, Samiaa Hamdy, Sherin Farghally European Respiratory Journal 2015 46: OA3264
Lung recruitment
Lung recruitment
USG & Recruitment Highly significant correlation was found between PEEP-
induced lung recruitment measured by PV curves and ultrasound reaeration score (Rho = 0.88; P < 0.0001)
ultrasound reaeration score of
≥ 8 : PEEP-induced lung recruitment greater than 600 ml
≤ 4 : PEEP-induced lung recruitment ranging from 75 to 450 ml
A statistically significant correlation was found between LUS reaeration score and PEEP-induced increase in Pa(O₂) (Rho = 0.63; P < 0.05)
USG : Pneumonia Four signs :
interstitial syndrome
abnormal pleural line
alveolar consolidation
pleural effusion
Combining four USG signs : sensitivity 94.6% for diagnosing CAP
Liu XL, Lian R, Tao YK, et al. Lung ultrasonography: an effective way to diagnose community-acquired pneumonia. Emerg Med J 2015;32:433-8
USG : Pneumonia
J Thorac Dis 2016;8(10):2822-2831
USG : Pneumonia 14 articles
LUS :
pooled sensitivity of 0.904 (0.884–0.921)
pooled specificity of 0.884 (0.861–0.904)
pooled + ve LR of 6.6 (3.7–11.7)
pooled - ve LR of 0.08 (0.04–0.19)
AUC: 0.9611
AUC for LUS and CXR was 0.972 and 0.867 respectively and the Z statistic of the two sROC curves was 2.31
USG - VAP Early diagnosis
Response to antibiotics
USG : VAP
USG : VAP Subpleural consolidation + air bronchogram had a
positive predictive value of 86% with a positive likelihood ratio of 2.8.
Two dynamic linear/arborescent air bronchogramsproduced a positive predictive value of 94% with a positive likelihood ratio of 7.1
PPV + ve liikelihoodratio
Subpleuralconsolidation + air bronchogram
86 % 2.8
2 dynamic linear/arborescent air bronchograms
94 % 7.1
USG : VAP
Sensitivity Specificity
VPLUS- EA 77 78
VPLUS 69 71
USG: VAP
USG : VAP Ultrasound score >5 was associated with a CT
reaeration >400 mL and a successful antimicrobial therapy
Ultrasound score <-10 was associated with a loss of CT aeration >400 mL and a failure of antibiotics
A highly significant correlation was found between computed tomography and ultrasound lung reaeration(Rho = 0.85, p < .0001)
USG : Prone ventilation
USG : Prone ventilation
sensitivity and specificity of ASV ≥5.5 for the PPP-positive group were 73.9% and 86.4%, respectively
USG : Post extubation stridor
Air column during balloon cuff inflation(hyperechoic)
True cords are over both sides of air column(hypoechoic)
Cartilages are behind the true vocal cords and beside the air column(hyperechoic)
Ding LW,Sand HC, Wu HD et al laryngeal usg a useful method in predicting post extubation stridor
USG : Post extubation stridor
Air column during balloon cuff deflation(air column width increased)
Ding LW,Sand HC, Wu HD et al laryngeal usg a useful method in predicting post extubation stridor
USG : Post extubation stridor
Median Non stridorgroup
Stridor group
Air leak vol 300 ml 25 ml
Air column width 6.4 mm 4.5 mm
Laryngeal USG- post extubationstridor
Cuff leak test : 75 & 59 %usg :50 & 54 %PPV of both < 20%
AIRWAY USG Assesment prior to intubation
Assessment prior to tracheostomy
U/S guided tracheostomy
ETT POSITION
Take home message USG over CXR
Pleural effusion
Pnuemothorax
Blue protocol in acute respiratory failure
Interpreting lung aerationWeaning from MVVAP Assessing prone ventilationLung recruitment
(needs further validation and uniformity)
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